A range of molecular technologies for the detection of a nucleotide sequence of interest (also referred to herein as a ‘target nucleotide sequence’) have been developed. Such methods have application in, for example, public health, the detection of pathogens in food or water, epidemiological studies, genetically modified organism (GMO) detection, medicine, clinical diagnoses, disease susceptibility diagnoses, tissue typing, blood screening, forensic medicine, bioweapon detection, molecular toxicology, gene therapy, and DNA tagging, among many other applications.
Current methods for detecting a target DNA sequence generally involve one, or a combination of, molecular techniques. These techniques generally fall into three groups loosely defined as sequence-specific detection, sequence-specific enrichment and signal amplification.
Most detection techniques gain their sequence specificity through base paring of complementary probes or oligonucleotides to a sequence of interest within the target DNA sample.
The two most commonly used DNA detection methods, polymerase chain reaction (PCR) and Southern blotting, differ in how they proceed from this point. The PCR method enriches a target DNA through a series of amplification cycles and signal detection can be, for example, though the use of stains, fluorescence or radiolabelling. Southern blotting involves no DNA enrichment step, but uses high-energy 32P for signal amplification. These extensively used techniques, though highly developed, still retain significant drawbacks. For PCR, the equipment required is expensive, the process is time-consuming and the degree of expertise required is high. Southern blotting often uses hazardous radioactive labelling, takes up to a week to complete, and requires large amounts of substrate DNA.
An effective biosensor for detecting a specific DNA sequence in a sample that addresses one or more of the deficiencies of the currently available techniques, without substantially losing target-specificity or sensitivity, would be desirable. Furthermore, such a technique would also ideally require a low capital input (particularly in the case of equipment requirement), minimal expertise or technique-specific training, and provide quick and accurate results.
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.